We report a bug in linux-4.17.19: "KASAN: use-after-free Read in ata_scsi_mode_select_xlat" kernel config: https://kt0755.github.io/etc/config-4.17.19 repro: https://kt0755.github.io/etc/repro.359bd.c (Not always works) In this example, a syscall ioctl (i.e., sg_scsi_ioctl) is trying to access data (drivers/ata/libata-scsi.c:4025), for some reason, which had been freed by usbdev_release function. ========================================= BUG: KASAN: use-after-free in ata_scsi_mode_select_xlat+0xd96/0x11b0 drivers/ata/libata-scsi.c:4025 Read of size 1 at addr ffff880117172003 by task syz-executor6/7232 CPU: 0 PID: 7232 Comm: syz-executor6 Not tainted 4.17.19 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xd2/0x148 lib/dump_stack.c:113 print_address_description+0x7f/0x2c0 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report+0x257/0x380 mm/kasan/report.c:412 __asan_report_load1_noabort+0x19/0x20 mm/kasan/report.c:430 ata_scsi_mode_select_xlat+0xd96/0x11b0 drivers/ata/libata-scsi.c:4025 ata_scsi_translate+0x33c/0x670 drivers/ata/libata-scsi.c:2015 __ata_scsi_queuecmd drivers/ata/libata-scsi.c:4340 [inline] ata_scsi_queuecmd+0x31c/0x780 drivers/ata/libata-scsi.c:4389 scsi_dispatch_cmd+0x49b/0xba0 drivers/scsi/scsi_lib.c:1761 scsi_queue_rq+0x1344/0x19c0 drivers/scsi/scsi_lib.c:2064 blk_mq_dispatch_rq_list+0x1e0/0x1a50 block/blk-mq.c:1242 blk_mq_do_dispatch_sched+0x1a0/0x410 block/blk-mq-sched.c:120 blk_mq_sched_dispatch_requests+0x454/0x740 block/blk-mq-sched.c:216 __blk_mq_run_hw_queue+0x145/0x210 block/blk-mq.c:1362 __blk_mq_delay_run_hw_queue+0x3da/0x540 block/blk-mq.c:1430 blk_mq_run_hw_queue+0x181/0x330 block/blk-mq.c:1467 blk_mq_sched_insert_request+0x2c0/0x770 block/blk-mq-sched.c:463 blk_execute_rq_nowait+0x14f/0x2f0 block/blk-exec.c:64 blk_execute_rq+0xe6/0x1c0 block/blk-exec.c:101 sg_scsi_ioctl+0x3bf/0x7b0 block/scsi_ioctl.c:509 sg_ioctl+0x1c6f/0x2e70 drivers/scsi/sg.c:1116 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1aa/0x10a0 fs/ioctl.c:686 ksys_ioctl+0x9e/0xb0 fs/ioctl.c:701 __do_sys_ioctl fs/ioctl.c:708 [inline] __se_sys_ioctl fs/ioctl.c:706 [inline] __x64_sys_ioctl+0x7e/0xc0 fs/ioctl.c:706 do_syscall_64+0xc4/0x4e0 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4497b9 RSP: 002b:00007f92fb915c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f92fb9166cc RCX: 00000000004497b9 RDX: 00000000200004c0 RSI: 0000000000000001 RDI: 0000000000000013 RBP: 000000000071bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000005c58 R14: 00000000006eecf8 R15: 00007f92fb916700 Allocated by task 7207: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc5/0xf0 mm/kasan/kasan.c:553 kmem_cache_alloc_trace+0x148/0x300 mm/slub.c:2768 kmalloc include/linux/slab.h:512 [inline] kzalloc include/linux/slab.h:701 [inline] usbdev_open+0x5b/0x760 drivers/usb/core/devio.c:975 chrdev_open+0x23a/0x640 fs/char_dev.c:417 do_dentry_open+0x826/0xe70 fs/open.c:794 vfs_open+0x123/0x250 fs/open.c:908 do_last fs/namei.c:3365 [inline] path_openat+0x665/0x29f0 fs/namei.c:3505 do_filp_open+0x1bd/0x2c0 fs/namei.c:3540 do_sys_open+0x35e/0x4e0 fs/open.c:1101 __do_sys_open fs/open.c:1119 [inline] __se_sys_open fs/open.c:1114 [inline] __x64_sys_open+0x89/0xc0 fs/open.c:1114 do_syscall_64+0xc4/0x4e0 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 7200: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x14d/0x1a0 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 slab_free_hook mm/slub.c:1388 [inline] slab_free_freelist_hook mm/slub.c:1415 [inline] slab_free mm/slub.c:2988 [inline] kfree+0x109/0x340 mm/slub.c:3944 usbdev_release+0x302/0x3a0 drivers/usb/core/devio.c:1058 __fput+0x2c7/0x780 fs/file_table.c:209 ____fput+0x1a/0x20 fs/file_table.c:243 task_work_run+0x151/0x1d0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x8ba/0x30a0 kernel/exit.c:865 do_group_exit+0x13b/0x3a0 kernel/exit.c:968 get_signal+0x6bb/0x1650 kernel/signal.c:2482 do_signal+0x84/0x1b70 arch/x86/kernel/signal.c:810 exit_to_usermode_loop+0x155/0x190 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:265 [inline] do_syscall_64+0x445/0x4e0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff880117172000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 3 bytes inside of 512-byte region [ffff880117172000, ffff880117172200) The buggy address belongs to the page: page:ffffea00045c5c80 count:1 mapcount:0 mapping:0000000000000000 index:0x0 compound_mapcount: 0 flags: 0x200000000008100(slab|head) raw: 0200000000008100 0000000000000000 0000000000000000 00000001800c000c raw: ffffea00043e7100 0000000500000005 ffff88011a003080 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff880117171f00: fb fb fb fb fb fb fb fb fc fc fc fc fb fb fb fb ffff880117171f80: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc >ffff880117172000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff880117172080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff880117172100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ========================================= Thanks, Kyungtae Kim
